Okay here's my deal. I've got a 400ex with a stock bore 11.1 weisco piston and a stage 2 hotcam. I cant seem to find the sweet spot on the jetting. I've tried from a 160 to a 210 jet. These are not Dyno jets either. Now i just finished running the bike with the current conf. of a 210 main, 1/2 a turn out on the air/mix screw, and the clip all the way down( towards the point) on the needle. And i still cant get the plug to turn a brownish color. Still white as can be. I've also tryed a hotter burning plug. I am completely stumped and dont know what the heck to do. So if anyone has any suggestions im up for any of them. Also i am right at sea level too. Thanks ahead of time.

 

What type of fuel are you currently using in your 400ex and if it is white you are running lean so you will need to jet up.

 

The mixture screw needs more than 1/2 turn out....or the pilot jet is too big. What size is the pilot jet?
If the plug is white...then going to a colder plug might be better, but a stock heat range plug should work fine.
Next issue...where exactly are you reading the plug at? If its right at the tip...thats not the place. Its way inside the "well" that the electrode is in. Did you do a proper plug chop first? I was reading an article in Car Craft, and it had a great picture of where youre supposed to check the plug, and how the plug chop is done.check this picture Note the spark plug in the picture has the threads removed, and how far into the porceline the smoke ring is.
Doing a plug chop isnt as easy as it used to be...newer gas has too many additives for clean burning, and the smoke ring isnt as pronouced as it should be. Usually its much better to jet to drivability issues. Once you no longer have drivability issues...its jetted correctly. Heres a good article on jetting, and it explains the drivability issues and how to correct and trouble shoot.jetting article

 

Aight guys, we did alot more testing last nite, and here's what we've come down too. Also just so you know we are burning 93 fuel. Here is what we've got now. 190 main jet, stock pilot, air/mix screw, 3.25 turns out, and the needle clip is one down from stock(had it all the way down and was way to much fuel). And like one of yall said, i gave up jetting to the plug, and jetted to drivability. Oh yeah, the air box lid is off, and am running a uni filter, with a curtis sparks x6 pipe. So im somewhere in the ball park but i beleive that the main jet might need to go down one more size. Going to do some more testing today, and ill be sure to let everyone know what i find out. Thanks for all the replys and the insight. Dont know what i would do without this place sometimes. Thanks again.